Process and apparatus for desiccating liquids



R. F. BARKER.

PROCESS AND APPARATUS FOR DESSICATING LIQUIDS.

APPLICATION FILED JUNE 23.1919.

1,362,590, Patented Dec. 21, 1920.

2 SHEETS-SHEET l- I 4 I 14 J5 .233 .13

.Zizuenz or.

R. F. BARKER. PROCESS AND APPARATUS FOR DESSICATING LIQUIDS.

APPLICATION FILED JUNE 23. 1919.

1,362,590, Patented Dec. 21,1920.

2 SHEETS-SHEET 2.

UNITED STATES PATENT OFFICE.

PROCESS AND APPARATUS FOR DESICCATING LIQUIDS.

Specification of Letters Patent.

Patented Dec. 21, 1920.

Application filed Uune 23. 1919. Serial No. 306,187.

To all whom it may concern-.-

Be it known that I, RICHARD F. BARKER, a citizen of the United States, residing at Bellows Falls. in the county of lVindham and State of Vermont, have invented or discovered certain new and useful Improvements in Processses and Apparatus for Desiccating Liquids, of which the following is a specification, reference being had therein to the accompanying drawing.

My invention relates to the separation of moisture from the constituent solids of liquids or semi liquids and recovering such solids in a substantially dry or desiccated form, and it has reference more particularly to the desiccation of milk, skimmed or whole, and of cream. The object of the invention is the desiccation of animal, vegetable. or other substances, normally in a liquid or semi-liquid form, the solids of which it is desirable to reduce to dryness quickly, and without substantial change to their chemical or physical structure.

Previous desiccating processes for liquids containing proteins, sugar, or like substances which are extremely sensitive to heat, have been mainly of two classes; .one, atomizing the liquid in a hot current of air, and the other, the drawing out of the liquid in a film upon a revolving surface and the subjecting of this film to heat from the surface, with'or without the additional drying effect of a hot-air current over the film. These processes, though successful, are slow in operation; the first requires vast quantities of heated air to effect complete desicca tion, and the second is slow because the film drawn upon the revolving surface must be of excessive thinness in order to dry before it is changed chemically by the heat to which it is subjected.

I have discovered that if the liquid to be desiccated, previous to being deposited in finely divided particles upon a heated surface, is preheated and partially evaporated by a hot current of air whilein'such afinely divided state, the desiccation is extremely quick and efficient. The desiccation is further accelerated, if the particles on the heated surface, before they are dried, are superimposed by other partially evaporated finely divided particles heated in a hot-air current and the wholedried' finally on the hot surface while subjected to a hot-air current. My process obviates the use of large quantities of hot air, and it does not require a great deal of time to evaporate a large quantity ofliquid.

The liquid to be desiccated is finely divided by any convenient method, such as a spray nozzle. The finely divided particles are then conveyed in a current of drying gas, preferably air, and before the evaporation of all the moisture which they contain, they are deposited on a hot surface which is preferably movable. The deposited particles on the surface are subjected to the action of hot air or other drying gas. While the particles when first attached to the hot surface contain considerable moisture, other partially dried particles are superimposed thereupon, these latter particles having also been partially evaporated be.- fore they reach the particles first imposed upon the hot surface. The superimposed particles are subjected to the action of a drying gas and the evaporated material is preferably removed previous to complete desiccation to avoid scorching, and this process may be repeated a predetermined number of times, depending on the material to be treated and the temperature of both the drying surface and the drying gas used. In the last application of the partially dried particle's, they, together with the particles previously deposited on the hot surface, are evaporated to a substantial dryness, or to a solid condition, by the heat of the surface to which they cling, and by the current of dry gas passing adjacent to this surface.

After being so dried, they are removed from said surface by any suitable means, in the 7 form of a thin desiccated crust or film which readily crumbles to powder.

, In the accompanying drawing Figure 1 is a sectional elevation of an apparatus b which my invention can be carried into e feet, and Fig. 2 is a cross section of the same on line 2-2, Fig. 1. Fig. 3 is an end elevation of the same, partly in section, on line 33, Fig. 1.

Referring to the drawing, 12 denotes a drying chamber into which hot air is forced through pipes 13 and 14. Mounted for vertical rotation in the chamber 12 is a hollow disk-like. drum 15 mounted on a horizontal axis consisting of hollow pipes 16 supported by suitable bearings, as 17, the said hollow drum being heated internally, preferably by steam conveyed to and from the chamber of said drum through the said pipes 16.

Communicating with the chamber of the i y the drying cham ranged closely adjacent to the ends of the nozzles 20.

The heated drum is slowly rotated in the direction indicated by the arrow in I 1g:

2 in the chamber 12, and the liquid being treated is sprayed into the drying chambers afforded by the hoods 18 and is partially eworated to a viscous condition in said cl. an ers, and is carried by the hot air currents in this partially evaporated and viscous condition onto the heated surfaces of the drum 15,- so that it will be dried on said drum in the formof a thin crust and will be removed therefrom by a stationary scraper or doctor, as 22, and when thus removed will be received in a suitable receptacle or trough 23 and will be carried outward in said trough by a helical c'onveyer, as 24, and discharged at anoutlet 25. These scrapers, troughs and conveyers willof course be duplicated at each side of the drum 15, as will'be understood. 4 t

In order to make a successive deposit of the particles to be evaporated on the surface of the heated rotating drum 15 a plurality of drying chambers afforded by the hoods 18 and into which chambers the liquid will be sprayed,

may be employed in connection with each surface or face of the drum. These drying chambers are arranged one behind the other in the direction of rotation indicated by the arrow in Fig. 2, of the drum 15, as Wlll be understood from Fig. 2. A conventional representation of these drying chambers is indicated b the dotted lines in Fig. 2, and

these cham ers may be arranged either' so as to overlap each other, as indicated by the dotted lines referred to, in the chambers will, partly communicate with each other as will be understood, or they may be so arranged as to be entirely separate. It will be understood that therewill be a liquid conveying pipe or nozzle and an air pipe or nozzle provided for each one of these drying chambers, although, for simplicity of illustration, these atomizing pipes and noz zles for the successivechambers are not duplicatedin the drawing.

Fromthe foregoing it will be understood that in the operation of the apparatus shown, and in carryingthe improved process into effect, the liquid or semi-liquid substance to be, desiccated will be sprayed into awoaoeo e r the dryingchambers 18 where it will be heated and partly exa orated and will be forced through said 'ciambers by." the air currents entering through the pipes 13 and 21 onto the rotatin heating drum 15 by which the complete esiccation of the material, into solid form, in a film or crust, will be effected; and the material thus desiccated may be removed from the surfaces of the drum by scrapers or doctors, as 22, and may be carried outward from the chamber 12 by conve ers, as 24. The conveyers 24 work in troug s 23 having discharging spouts 2.5.

The drying chamber 12 is provided with an exit-pipe 26 through which the hot air, more or less moisture laden, can escape from said chamber.

I find'that the temperature to which it is necessary to heat the drum 15, as well as that of the gas or hot air also used for preheatingand partially evaporatin the particles -.may be varied to a consider-a le extent andv the product no morethan a longer exposure at a lower temperature I find it is preferable, however, in producing a soluble milk product, to heat the drum to/rte'mperature of 150 F., or somewhat higher, and to limit the initial temperature of the drying gas orhot air, entering through pipes 13, to about212 F. In the treatment of milk for iprodiicing a soluble dry product it is not necessary, however, that the temperature of theair entering the spraying pipes 21 should be at a relatively low temperature,

as muchof the heat is immediately'absorbed ..in the spraying" process so that the air under pressure entering through the said pipes 21 ma be considerably more than 212 F.

ut in producing a milk powder which is not wholly soluble, owin'g to coagulation.

of the albumen but which is readily saleable for bakersuse, etc'.-,' "'and which may 'be manufactured more cheaply and quickly than the soluble product, much higher'temperatures than those, above referred to may be employed. In such case the rotating druiii 15 may be heated to a temperature of 300 F., or over and a much smaller volume of highly heated air, approximately of the temperature of the drum, may be employed; the drying being done largely by the drying drum; while in producing a completely soluble product. it is. done. largely by the heated air. From this it will be understood that in ,the lise of my improved apparatus, and in practising my improved process, the range wide.

One advantage of my improved process in which the material to be dried .is first partially evaporated before'being applied to a moving heated surface, (.OIlSlSt-S in the fact that the partially evaporated particles in being applied to the heated surface form a rough or irregular surface which affords a greater evaporating quality than a smooth film would; so that the drying process, comprising the use of heated air, proceeds more rapidly than it would if the heated air were brought into contact with a smooth filmon the heated drying surface of the drum 15.

In the case of liquids having a moisture content of 80% or more, it may be advantageous, though not necessary,.to condense the liquid b any suitable process, so that the total so ids shall exceed 20 per cent., before desiccating the liquid by my process, as this enables me to increase the rate of desiccation perceptibly. This, in the case of highly organized albuminoid bodies, has the additional advantage of allowing a greater heat without injuriously affecting the product, as a concentrated liquid, such, for instance, as milk, will stand a much higher heat for a short period without affecting the solubility of the final product, than were it unconcentrated.

The invention is not to be understood as being limited to the use of an apparatus such as is herein shown and described, or to the particular steps of the process hereinbefore set forth, as considerable variations from the described apparatus and process may be made within the scope of the appended claims or the scope of mechanical skill, without departing from the essence of the invention.

Having thus described my invention or discovery, I claim and desire to secure by Letters Patent:

1. The process of desiccatingliquids consisting in atomizing and partially evaporating the liquid in a drying atmosphere, collecting the atomized and partly dried material, while in a viscous condition, upon a moving heated surface, further drying said material on said heated surface to obtain a solid residue, and removing the said residue from the said surface.

2. The process of desiccating liquids which consists in atomizing the liquid in a drying atmosphere, by a hot current of air, carrying the atomized and partially evaporated viscous material onto a moving heated surface, by said hot current of air, further drying the material on said heated surface to obtain a solid residue, and removing the said residue from said surface.

3. The process of desiccating liquids which consists in atomizing and partially evaporating the liquid in a drying atmosphere by a hot air current in a drying chamber,

depositing the partially evaporated viscous particles on a moving heated surface in such a manner as' to produce an irregular or rough film by the successive accumulation degree'of concentration into and through a plurality of successively arranged chambers each of which has a drying atmosphere afforded by hot air currents forced therethrough, and thus heating and partially evaporating the material in said chambers,

successively depositing the partially evap: orated material on a moving heated surface thereby forming successive layers of said material on said surface, further drying the material on said surface to reduce the same to solid form, and then removing the'desiccated material from said surface.

An improved apparatus for desiccating liquid or semi-liquid substances, consisting of the combination with a hollow rotating disk or drum and means for heating the same internally, of a drying chamber inclosing said disk or drum, hot air pipes communicating with said chamber, hoods arranged on opposite sides of said disk or drum and communicating with said chamber and with the chambers of which hoods said hot air pipes communicate, means for spraying the liquid or semi-liquid substance to be evaporated into the chambers of said hoods and onto the opposite surfaces of said disk or drum, and means for removing the desiccated material from said disk or drum. 6. An improved apparatus for desiccating liquid or semi-liquid substances, consisting ofthe combination with a hollow rotating disk or drum and means for heating the same internally, of a drying chamber inclosing said disk or' drum, hot air pipes communicating with said chamber, hoods arranged on opposite sides of said disk or drum and communicatingwwitlr'saideliamber, and with"tlie chambers of which hoods said hot air pipes communicate, means for spraying the liquid or semi-liquid substance to be evaporated into the chambers of said hoods an onto the opposite surfaces of said disk or drum, and means for removing the desiccated material from said disk or drum, a plurality or succession of said hoods being provided for each face of said disk or drum. v

In testimony-whereof I afiix my signature.

RICHARD F. BARKER. 

